In body-on-frame vehicle architecture, a vehicle body mounts atop a vehicle frame in a two-piece construction. Typically, the vehicle frame comprises a pair of side frame rails interconnected by a plurality of cross members. Vehicle drive line, suspension, and body subsystems mount to the frame. The vehicle body includes a rocker panel extending between front and rear fenders below a door panel. In a closed position, a vehicle door overlies a portion of the rocker panel. In conventional body-on-frame vehicles, a gap exists between the rocker panel and the frame rail following assembly. In a side impact collision, plastic deformation of sheet metal disposed within the gap closes the gap prior to energy transfer to the frame rail.
Modern vehicles usually employ a vehicle sensing and diagnostic module (SDM) for detecting a vehicle impact and effecting air bag deployment when acceleration from the impact exceeds a predetermined threshold. The SDM typically includes an accelerometer mounted to the vehicle body inboard of the frame rails for sensing the acceleration.